maximum possible number atmost k swaps

// C++ program to find maximum 
// integer possible by doing 
// at-most K swap operations on 
// its digits. 
#include <bits/stdc++.h> 
using namespace std; 
  
// Function to find maximum 
// integer possible by 
// doing at-most K swap operations 
// on its digits 
void findMaximumNum( 
    string str, int k, 
    string& max, int ctr) 
{ 
    // return if no swaps left 
    if (k == 0) 
        return; 
  
    int n = str.length(); 
  
    // Consider every digit after 
    // the cur position 
    char maxm = str[ctr]; 
    for (int j = ctr + 1; j < n; j++) { 
        // Find maximum digit greater 
        // than at ctr among rest 
        if (maxm < str[j]) 
            maxm = str[j]; 
    } 
  
    // If maxm is not equal to k, 
    // decrement k 
    if (maxm != str[ctr]) 
        --k; 
  
    // search this maximum among the rest 
    for (int j = ctr; j < n; j++) { 
        // If digit equals maxm swap 
        // the digit with current 
        // digit and recurse for the rest 
        if (str[j] == maxm) { 
            // swap str[ctr] with str[j] 
            swap(str[ctr], str[j]); 
  
            // If current num is more than 
            // maximum so far 
            if (str.compare(max) > 0) 
                max = str; 
  
            // recurse other swaps after cur 
            findMaximumNum(str, k, max, ctr + 1); 
  
            // Backtrack 
            swap(str[ctr], str[j]); 
        } 
    } 
} 
  
// Driver code 
int main() 
{ 
    string str = "129814999"; 
    int k = 4; 
  
    string max = str; 
    findMaximumNum(str, k, max, 0); 
  
    cout << max << endl; 
  
    return 0; 
} 
// C++ program to find maximum 
// integer possible by doing 
// at-most K swap operations 
// on its digits. 
#include <bits/stdc++.h> 
using namespace std; 
  
// Function to find maximum 
// integer possible by 
// doing at-most K swap 
// operations on its digits 
void findMaximumNum( 
    string str, int k, string& max) 
{ 
    // Return if no swaps left 
    if (k == 0) 
        return; 
  
    int n = str.length(); 
  
    // Consider every digit 
    for (int i = 0; i < n - 1; i++) { 
  
        // Compare it with all digits after it 
        for (int j = i + 1; j < n; j++) { 
            // if digit at position i 
            // is less than digit 
            // at position j, swap it 
            // and check for maximum 
            // number so far and recurse 
            // for remaining swaps 
            if (str[i] < str[j]) { 
                // swap str[i] with str[j] 
                swap(str[i], str[j]); 
  
                // If current num is more 
                // than maximum so far 
                if (str.compare(max) > 0) 
                    max = str; 
  
                // recurse of the other k - 1 swaps 
                findMaximumNum(str, k - 1, max); 
  
                // Backtrack 
                swap(str[i], str[j]); 
            } 
        } 
    } 
} 
  
// Driver code 
int main() 
{ 
    string str = "129814999"; 
  
    int k = 4; 
  
    string max = str; 
    findMaximumNum(str, k, max); 
  
    cout << max << endl; 
  
    return 0; 
}